Numerous materials capable of reversibly exchanging lithium ions have been investigated for the development of rechargeable lithium ion batteries. Lithium titanate, i.e., Li4Ti5O12, is a promising active anode material for these batteries. See Ohzuku et al., Journal of the Electrochemical Society, 142, 1431 (1995); and Thackeray, Journal of the Electrochemical Society, 142, 2558 (1995).
High performance lithium ion batteries require nanostructured lithium titanate particles. Lithium titanate particles prepared by conventional solid state reactions have micron-sized particles, thus failing to meet the high performance requirement. Furthermore, solid state reactions consume a significant amount of the energy as they take place at a very high temperature (e.g., over 800° C.) for a long time (e.g., 24 hours). On the other hand, hydrothermal synthesis affords nanostructured spinel lithium titanate. See Tang et al., Electrochemistry Communications 10, 1513 (2008). However, the hydrothermal method suffers from low yields and is not suitable for mass production.
There is a need to develop a convenient method for preparing nanostructured lithium titanate particles with a high yield and at a low cost.